


The Prisoner of Azkaban's Brother

by Captain_Aesthetics



Category: Harry Potter - J. K. Rowling
Genre: (in a sexy way), Alternate Universe, Biting, Domestic, Hurt/Comfort, I don't trust Dumbledore and you can tell, M/M, Professor Regulus Black, Regulus Black Deserves Better, Regulus Black Lives, Regulus Black-centric, Rough Sex, Sassy Regulus Black, Werewolf, come find me, sorry about all the Regulus tags, you are my people
Language: English
Status: Completed
Published: 2020-07-16
Updated: 2020-07-28
Packaged: 2021-03-04 21:29:26
Rating: Explicit
Warnings: Major Character Death
Chapters: 3
Words: 13,585
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/25043179
Author URL: https://archiveofourown.org/users/Captain_Aesthetics/pseuds/Captain_Aesthetics
Summary: What if Regulus Black was the Death Eater spy with the cushy Hogwarts teaching post? And all that that entails.
Relationships: Regulus Black/Remus Lupin
Comments: 28
Kudos: 187





	1. Professor Dumbledore's Big Mistake

**Author's Note:**

> Here are some things you should know:  
> \- JK Rowling is a gross terf  
> \- Regulus Black is my favorite Harry Potter character  
> \- Regulus/Remus is my favorite ship, ever  
> \- I (very recently) was musing about how people who write 5-digit wordcount fics are wizards and good for them but it couldn't be me  
> \- I saw a tumblr post that was like "hey wouldn't it be funny if..."  
> \- then this happened  
> \- It's finished, I'm just spreading out posting. Entire thing clocks in at around 13K words. This will not be abandoned. I have trust issues when it comes to WIPs and would never do that to you.

_Dumbledore walked right up to the boy clinging to the gates of Hogwarts. He was young enough he wondered if it was a student who had gotten lost, one of the orphans who didn’t want to leave for the summer. He was dripping wet, though Albus couldn’t remember the last time it had rained. Yet he did not open the gate. Not yet._

_“My boy. What is it?”_

_The boy lifted his head. His stance was not anguish but exhaustion of the body. It was giving out from under him yet he held himself upright by the iron bars of the gate, mustering every scrap of dignity he could. “Let me in. Let me stay. And I’ll tell you everything.”_

_“About?”_

_“What do you think?” He lifted his sleeve to reveal the skull and snake tattoo. “Everything.”_

_He did not tell everything. He told enough._

* * *

Remus was surprised by three things when he walked into the potion master’s cupboard his first week as a professor at Hogwarts, a month before the students arrived. One, that Regulus Black was the potions master. Two, that he already knew Remus was a werewolf. And three, that Regulus didn’t seem to mind.

“So,” he’d said in a voice pitched low. “You’re a werewolf.”

“Excuse me?”

“Oh don’t bother,” he said, smiling and leaning against one of the shelves, making the jars clank against each other. “I know, and I know Dumbledore wanted me to know. He came to me a month ago, asking if we were stocked up on alconite. He could have looked himself. But I told him yes and asked why. He was cagey of course, probably waiting for you to accept the job offer. Why else would someone need large quantities of alconite unless they were making wolfsbane, and why would he need wolfsbane unless he was about to hire a werewolf?Then you show up. Obvious. Ever had this stuff before?”

“Wolfsbane?” Remus said, still shocked from everything else, no room to be shocked at referring to what many werewolves considered to be salvation as “this stuff.” “No, no I haven’t.”

“Fascinating. Not shocking, very few have, due to the expense and complications. Even fewer willing to go on the record. I’ll make it for you if you promise to report all symptoms and reactions.”

“Sure,” said Remus, who would have done anything for it. 

“Good. I’ve already started a batch. You can collect your first dose in my quarters tonight.”

It had been so long since he’d talked to one of the Black children Remus had forgotten it was like that. An onslaught of personality that he had to cling to or get left behind.

He hadn’t remembered Regulus as being like that. When they’d been students Regulus had been the quiet one. That he knew of anyway, compared to Sirius and compared to his own housemates. He had a gravitas lent to him by his name and a fair amount of deference was paid. He benefited from that while Sirius seemed to feel the need to rise above it, win friends on his own merits. Regulus seemed to think the less said, the better. Sirius felt otherwise, though what he said wasn’t always true, as everyone found out too late. 

Either Regulus had come into his own or war had changed him. Remus had barely gotten two words in edgewise during the whole encounter. He felt knocked back to being a child again, like he couldn’t be at Hogwarts and not be reduced to a stammering teen.

He arrived at Regulus’ quarters at 8pm, a respectable time that wouldn’t seem too eager. The room had the air of full time lodging. Remus had been to many of the other professors’ rooms by then, after invites for tea and sympathy, many of them remembered him as a student. Their quarters had each been cozy in their own way but had the temporary decor of a person who has somewhere else to go when school is not in session. Not so with Regulus’ rooms. 

He didn’t know what he expected from him, probably nothing at all since he was still so blindsided by the whole encounter. For starters, he lived in one of the towers and not in the basement. The room was large-ish and round, everything from bed to bookshelves to table out in the open. The bookshelves were full and there was a pile of used cauldrons stacked in a corner. It wasn’t cozy but it was completely lived in with the clutter of someone who stayed there so long they didn’t notice it anymore. If they were to clean they would instantly lose track of where anything they needed could be.

Regulus himself sat at a large table that seemed to be where he both studied and ate. Remus was glad to see that his workbench was kept seperate, a cauldron slowly bubbling over faded embers, emitting a stale grassy odor. Regulus was hunched over a bowl and a book when Remus walked in, though he straightened immediately. 

“There you are,” said Regulus. “I was doing some supplementary reading. I need to know what symptoms there are before I know if they go away, after all.” 

“You could just ask,” Remus said, already feeling impatient. 

“Good, I’m glad you feel that way.” Regulus got up and grabbed a large brass tankard. He ladled some of the grassy potion into it and Remus realized with dismay that this was wolfsbane. He’d heard rumors it was foul tasting but there was no way to prepare for the real thing. Regulus walked over to him but didn’t hand the tankard over. He seemed to be holding it back. “There are some social aspects to being a werewolf, aren’t there? Outside of transformation.”

“You mean the tendency to form packs?”

“Sort of. More like pack behavior.” 

“I don’t follow.”

“A certain agitation? Like you want to drink this and go be alone for a while?”

That was exactly how he felt. But Remus thought there was no way Regulus could know why, until he really took in the way he was standing and the way he was waiting for his answer until he handed over the potion. Remus swallowed heavily and the desire to be alone went away very fast. 

“Everyone who has taken it said it mellows the worst aspects of being a werewolf. I thought that was a way of mitigating expectations. But maybe it was a promise.” He held out his hand. “Do you want to find out?”

Without a word, Regulus handed over the tankard. When Remus took it from him he started undoing the buttons on his robe. Remus' eyes never left Regulus as he drank every last drop of his potion. By the time he wiped the remnants from his mouth and set the flagon down on the counter, Regulus was down to shirt and trousers, both hanging open. Remus reached out, placing tender fingertips on Regulus’ collarbone. 

“Why did you stop?” Remus asked him, bold fingers moving past the borders of his clothes to explore what was yet unseen. 

Regulus held still to let him. “I’m not going to do everything for you. You have to want it. For the experiment.”

“So do you.”

“I asked you here didn’t I?”

Remus flattened his palm and slid it down the length of Regulus’ chest, pushing past the waistband of his trousers to hold his cock in his hand. He kept his eyes on his face, watched his eyelids flutter closed. “Bed,” he said. “Now.”

Regulus got into bed and for the next hour did everything he was told. Remus had his every touch met with a sigh or moan or shiver of pleasure. For two men each used to loneliness, that was all it took to start sleeping together.

* * *

By the end of one week they felt there was conclusive evidence that wolfsbane did not have an effect on lupine libido, though they agreed they should check during the next moon cycle, to be sure. 

“And a control,” said Regulus. “When the moon is new. Perhaps this has more to do with you than your… affliction.” 

Again, Remus should have been mad that Regulus made light of his condition when he got all the benefits and none of the complications. Despite the potion maintaining his mind and reason, Remus still had to go through the pain of transforming and turning back. Still, he did just screw Regulus into his own bed, grabbing him by the wrists and pinning him down while he had his way with him, when normally he’d be rocking his hips against a lumpy mattress and moaning into a pillow. Regulus might be trying to save face, after the mewling noises he made not ten minutes previous. 

Remus tried to make him make that sound every time they were in bed. It wasn’t difficult yet rare enough to be rewarding, real enough that Remus could feel it reverberating under his hands. Within a month Remus had all but moved in with Regulus. He was more likely to give notice he wasn’t available to sleep over than request that he could. Remus felt sated for the first time in his life. 

One night Remus had eaten dinner in his rooms while he worked on some final lesson plans before he let himself in to Regulus’ room. He knocked once to announce himself as he stepped inside. Regulus stood at his cauldron stirring steadily. 

“Make yourself comfortable, I had an idea,” Regulus said, not turning from his work.

“Oh?”

“Yes. This potion creates a lot of residue, it wastes a lot. I thought experimenting with the stirring pattern might help reduce it. It does make it a very high maintenance potion but for all that’s in there it’ll be worth it. Of course if I figure out the right pattern I can write a charm to automate it. Lie down, feel free to get started.”

Remus laughed. “How could I not, when you talk dirty like that?”

“You wound me.”

“It’s interesting! But not, well, stirring.”

“If you just made a pun feel free to see yourself out.” 

Remus laughed again, a soft chuckle as he lay down in bed. He watched Regulus’ back as he worked, his neck taut as he peered into the cauldron. His hair was tied back but strands had broken loose and steam-plastered to the side of his face. The fingers that weren’t holding the stirring rod drummed against the table. Yet for all of that he looked relaxed. As happy as a man could be, judging by his back. Remus, true to his word, did not have an amorous thought but instead felt a wave of contentment that was his last conscious thought until morning. 

It was the brightness of the sun that woke him, even though Regulus was snoring lightly right against his shoulder. He had drifted off the night before, fallen asleep in his clothes, one foot still on the floor. When Regulus finally finished his work for the night he’d turned to see him there, eyes shut, mouth parted in sleep. Without giving it much thought Regulus had charmed Remus’ shoes off before he manhandled him to the center of the bed, to sleep the sleep of the truly exhausted. Regulus changed into pajamas and climbed over him to his side of the bed, where he curled up against his side and went right to sleep.

It seemed the less said the better. What was there to say? Not much to each other. Regulus had always preferred to show how he was feeling rather than say it aloud to the object of his feelings. Expressing himself to disinterested parties was a non-issue. During his monthly afternoon tea with Dumbeldore, it came up almost immediately. 

“I think it would be wise to arrange for Remus’ things to be brought into my room and to gain permission for an expansion charm on the walls?”

“Oh,” said Dumbledore. “Why?”

“Interesting. I assumed you knew everything that went on in his castle but if you don’t that’s useful information. You’ll have to look into your painting of merchants you hung up right outside my door upon arrival, they must be sleeping on the job if they haven’t alerted you to my whereabouts.”

“It sounds like your whereabouts have been the same as always.”

“Ah, but you were always more interested in who I had for visitors. So you must know. Or are you merely asking for details?” He gave a lecherous wink.

“Have you discussed this with Professor Lupin?”

“No. Why?”

“Do you think he might have an opinion on the matter? Perhaps he likes his space.”

“If he doesn’t, can he move in? Or would you rather have your professors stumbling from room to room.”

“I would like my professors to comport themselves in an orderly manner.” 

“That would be ideal but not the reality, when love and sex are on the line. Isn’t that right, Professor?” Regulus’ grin did not falter under Dumbledore’s steely glare. He’d known that scrap of information about Dumbledore’s past for a long time and had been waiting to use it. He thought perhaps he should have saved it for something more important than moving in with his lover but then again, Dumbledore’s flirtation with fascism was something he could use against him more than once. Now Dumbledore knew that he knew, and they could stop pretending Regulus was the only one with a dark past. 

Regulus had a very frank relationship with secrets and misdeed. Eleven years ago he had walked into the very room where he was now drinking tea and offered everything he knew in exchange for protection. At least in that sense, their bargain had held up well. He had a lot of information, Hogwarts offered a lot of protection. He’d lived in relative comfort ever since. Monastic, slightly boring, but he’d had enough excitement for a lifetime already. 

Dumbledore sighed heavily. “If Professor Lupin comes to me with the same request it is yours. But if this winds up being a gambit for larger living quarters and you break up with him too soon, I will move you back to the basement.”

“No! There is mold! And students!”

“One of these days I will decide you aren’t joking.”

“I keep telling you plainly I’m not.” 

Dumbledore only hummed. Every Hogwarts professor received mixed reviews from students but none were so polarizing as Regulus Black’s. Dumbledore was well aware of which students in particular accused him of being too harsh. Mainly Slytherins who were shocked and dismayed that their own head of house would take points away from his own students at a rate commensurate with the other houses. Every first year who even sniffed dissent got detention and a lengthy speech about rewards only meaning something if they’re truly earned them, otherwise they led to a lifetime of self doubt and he would not set his own house up for failure like that. He would not have it said they only won by cheating. That was for Gryffindors. 

He certainly would not have it said he was fucking a Gryffindor, especially being fucked by one. He required discretion, though he was old enough now that most of the students assumed he was a monk already, if they thought about it at all. 

When it came to vulnerability, he would prefer one big show of emotion by asking Remus to move in with him rather than a daily tiny indignity of veiled hints about popping by after dinner or in the afternoon for tea. Remus could move in and they could move on with their lives. 

“Do you want to move your things in here?” Regulus asked over their next tea. “The room is expandable so it would be less cramped if you wanted to make this permanent.” 

“Is it? I didn’t know the castle would allow that,” said Remus, which was as good as a yes. His things were there by the evening. Regulus didn’t go to Dumbledore immediately. It was worth testing that they could stand each other’s presence in close quarters a few days before the relief of a widened room and a small partition for when they needed to grade papers or plan lessons. Hogwarts wasn’t, after all, Albus Dumbledore’s Rehabilitation Home for Stolen Youth; they were there to work.

* * *

Regulus’ complacency came from a history of being in the wrong place for so long it became the right place. He stayed a Death Eater long after he stayed up nights sobbing about what he’d done. He was smart and broken enough to keep those breakdowns hidden and by no more virtue than cowardice and noble blood, became a member of the inner circle. It was perverse. He had done nothing to earn it and did not want to, nor did he have any respect for the ones who did do things to earn it. 

Sometimes he suspected Tom knew he was a coward. It made him trustworthy, because cowards could be counted on to stay. It wasn’t Tom’s fault he overlooked that everyone had a breaking point, the point was very far away for most people with whom he kept company. And there was a difference between breaking and doing anything about it. 

It was, in fact, being asked to do something that woke Regulus up. When Tom disclosed the nature of horcruxes to him he was too numb to be horrified. It was when Tom asked Regulus to secure the location of one of the horcruxes that he betrayed him. That’s something he knows about himself, despite anything he’s done since. There’s no word for an unfinished horcrux: a wizard who breaks their own soul and has no place to put it.

At the age of eighteen, to save the life of a house elf, Regulus did something.

Regulus had, through action, saved more lives than he’d taken. But neither number was zero.

* * *

Dumbledore called a briefing for the teachers just before the start of term. There was the sense of excited clamor about them, not dissimilar to what the children would be feeling on Platform 9 ¾. The realities of the school year would be felt soon enough but Hogwarts was strange when it was empty. Everyone would be happier when it was full. 

Dumbledore gave everyone his usual half-smile and they went quiet. “No doubt you are aware that Sirius Black has escaped from Azkaban.” 

All eyes turned to Remus. They weren’t even subtle about it. Remus’ expression did not change, which was useful information to Regulus. He didn’t fail to note that no one spared a glance for him, not even Dumbledore who had failed to mention it at any of their meetings. No one expected him to know anything about his brother. They weren’t wrong but that didn’t mean it didn’t sting. 

Dumbledore also hadn’t mentioned the dementor patrol at their meeting either. Likely under an assumption Regulus wouldn’t make a fuss in public. Not because Regulus was afraid of fuss, they both knew he wasn’t, but showing weakness was something he avoided at all costs. While Dumbledore explained the grim necessity of dementors, Regulus tried to formulate a case against the dementors that didn’t boil down to he was scared of them and didn’t want them there and came up with nothing. So he kept his mouth shut, even when Remus volunteered to chaperone the students on the Hogwarts Express. 

Remus seemed pent up the rest of the day. Overthinking. Regulus forced the issue by climbing into his lap and kissing him soundly. They got him to stop thinking for a while. Regulus had to stop himself from thinking of the many reasons why news about Sirius Black made Remus eager to fuck but reticent to touch.

* * *

Two days before the students arrived Regulus said, “You know he’s going to be there, don’t you?”

“I’ve thought about little else.”

“And yet you haven’t asked me, his professor for the last two years.”

“I want to form my own opinion.” 

“All right,” said Regulus skeptically. 

Regulus was putting the finishing touches on his lesson plans before heading down to the feast. He heard the rumble of arrival, the teachers and older students making their way through the castle. He caught snippets of their conversation. “Attack” and “kiss” and “fainted.” He gathered up his robes and swept out of his office. If there was an attack on the train it wasn’t hard to guess the focus of that attack. Two years in and already it was clear that Harry drew trouble. 

Regulus couldn’t see Harry anywhere but he saw Remus, pulling on his professors robes for the first time as he walked into the Great Hall. Regulus jogged to catch up with him and grabbed his elbow to slow him. “What happened?”

“A dementor got aggressive on the train. It’s fine now. I was there and no one was harmed.” 

“What do you mean you were there?”

“I was in the compartment with Harry. I conjured a patronus and had some chocolate on hand. Harry fainted for a spell but revived easily. Pomfrey is looking over him now anyway.” 

“You were there.”

“It had no interest in me. Truly, it’s fine.”   
“It had interest in a thirteen year old.”

“Yes, that is troubling. I’ll write up a report for Dumbledore this evening.” 

Regulus was unable to offer any public comfort. He spent the feast stealing glances at Remus but he seemed fine, a placid smile laid over his face the entire evening. It only fell once they were back in their rooms. Remus sank into a chair at their table and conjured a quill, ink, and paper. Regulus poured firewhiskeys for both of them and took out another bar of chocolate. He hadn’t been anywhere near the dementor but he felt the need, knowing they were out there, circling the grounds. 

Remus had a quill in hand but wrote nothing. Regulus waited a moment, then said, “He looks just like his father, doesn’t he?” 

“Spitting image!” Remus said. He drank his firewhiskey in one gulp. Regulus refilled it for him “It’s been thirteen years and yet… Merlin, I almost checked the car for Peter and-”

“So did I,” Regulus said, cutting him off, though he heard Remus cut himself off as well. “When he was first in my classroom. It’s uncanny. His eyes are different though, that’s how I knew it wasn’t James.” 

“They’re his mother’s eyes.” 

“Does he know who you are?”

“No.”

“Why did you not take him? I wondered, when I heard where he has been living.”

“I tried. Dumbledore said he was safer with his family. He’s probably right.”

“They’re Muggles.”

“I’m a werewolf.”

Regulus, who hadn’t even considered that that would be a problem, sat with mouth agape. 

“This is the first stable job I’ve had. Before that it was jobs for Muggles with generous sick leave policies who wouldn’t notice the pattern of absences. Any job with wizards I’d have to quit after a few months. I have the house my parents left me but it’s in the middle of nowhere, no place to raise a child, no way to make friends. At least with his family he didn’t have to worry about food and lodging.”

“Hmm,” said Regulus, who decided Remus had learned enough that day. “Other than that, how was your first day, Professor?” 

“Ask me tomorrow, I can’t think of anything else.”

“Nothing else? Really?” He waggled his eyebrows and it was Remus’ turn to stand agape. 

“Are you serious?”

“No, I’m Regulus.”

“You’re a menace is what you are.”

“Get into bed.”

Regulus had a page in the back of his notebook where he charted Remus’ moods. That was the biggest downside he’d found to living together: he had to work harder to hide his notes. Remus’ moods were generally mild, until bed. Then he was everything from soft and tender to nearly frightening. Regulus wanted to chart if the moon had any influence. He was sure Remus would not approve. 

Regulus sank into Remus’ lap, stroking his face as he kissed him. He made himself pliable. It was a relief to let go. He’d been holding himself taut as a bowstring for years. What good was protection if he couldn’t relax? Now finally, he was starting to, right when he really shouldn’t be. 

After a decade Regulus had just been starting to feel comfortable in his teaching post. He was better with children than he’d expected, knew enough about potions to pass that information along so his students could get decent OWLs, and had been safe from bodily harm for the first time in his life. Then Quirrell was hired as the Defense Against the Dark Arts Professor, and all that that entailed. Voldemort choosing Quirrell to be his corporeal vessel meant one of two things. Either he didn’t know about Regulus working at Hogwarts at all or he knew Regulus was well and truly lost to him. Maybe it was because Regulus rarely left the borders of the school and then only to Hogsmeade. Maybe Quirrell was in the wrong place at the wrong time. Voldemort must know he was here now and Regulus would need to do a lot of lying if he wanted to be a double agent again. 

He didn’t. But Dumbledore might want him to, which meant he would. Regulus wondered if he could convince Remus to stand up to Dumbledore on his behalf by the end of the year. He doubted it, but it was a beautiful dream. 

Remus’ teeth scratched Regulus’ neck, yanking him back to the present. Regulus shuddered uncontrollably, obviously frightened. He froze, worried Remus would be offended by his fear. He was not. He growled and nipped at his shoulder. 

“Afraid I’ll turn you?”

“No,” Regulus gasped.

“Liar.”

“You wouldn’t do that to me.”

Remus put a hand to his throat, pulled Regulus’ head back so his ear was against Remus’ lips. “What do you know?” he hissed.

Regulus could only moan.

* * *

They never ever talk about the war.

* * *

Regulus returned late one evening. Remus looked up and saw him taking off his outdoor cloak. The air has just started to turn chilly. Without asking Remus conjured a second teacup and filled it from the pot he had encased in a warming spell next to him on the table while he read.

“Out for a stroll?” Remus asked. 

“Visiting Hagrid.” 

“Oh? How is he? I heard there was some kind of dust-up with a Hippogriff the other day.”

“Malfoy egged one on and then tried to blame the poor beast. Came to class moaning and groaning about his arm too hurt to do any of his work. So I told him he’d get a zero for the day and every day after he couldn’t do his work. And what do you know, his arm healed miraculously!” Remus laughed. “I wanted to check on Hagrid and the ‘griff though. They are delicate beasts after all. Hagrid offered me a drink and I nearly wound up under the table, thank you for this.” He downed the tea poured in one swallow and refilled it, finally looking to Remus. He was giving him such a tender look Regulus instinctively hunched his shoulders. “What?”

“You’re very-”

“Ridiculous.”

“Sweet.”

“Soppy.” 

“Kind.”

“You take that back.”

“No, shan’t. In one day you’ve aided in animal welfare, consoled a colleague, and done more to restore Slytherin’s reputation than a dozen heads of house before you.”

“I won’t let them grow up to be entitled pricks. And I’m going to make you Gryffindor maniacs actually earn your points. I refuse to be your foil only to be defeated in the final hour. It drives Albus crazy, which is another bonus.”

“Didn’t he save your life?”

“Alright? Am I to be indentured to him forever? I won’t betray him but I’m allowed my moments of needling him. For fun.”

“Hmm.”

“You should try it. You’re only going to be here a year anyway.” 

“What?”

“Position’s cursed, don’t you know. No DADA professor has lasted longer than a year, you won’t be back for another fall term. Get your shots in while you can.”

“I see.”

“It will be fun sneaking away to Hogsmeade for trysts though. I think I’ll enjoy that.” He looked around to see Remus gaping at him. Playing back what he just said he supposed it did sound like he didn’t expect their relationship to outlast Remus’ job so he added, “I will miss you snoring in my ear though.” 

“I don’t snore!”

“You do, a bit. It’s cute.”

“I am not cute!”

Regulus snorted. “Have you looked in a mirror lately love? You’re adorable.” He pinched his cheeks, to demonstrate. In retaliation, Remus grabbed his ass in both hands. Regulus made a noise both surprised and appreciative. 

“I know this is just payback for calling you sweet just now.”

“It really isn’t,” Regulus said but any further negotiation on the matter fell by the wayside. Regulus’ skin was still quite cold and in need of warming up.

* * *

Remus used his assigned rooms for transformations. In October, after Regulus spelled the door locked for him he waited outside, leaning against the door to hear what happened. Two Ravenclaw prefects gave him a look as they walked past. He said “shouldn’t you be in your dorms” with his most aristocratic disdain and they kept walking. 

He didn’t recognize the sound at first, then he realized it was whimpering. He did hear the moment it became inhuman. It was closer, just the other side of the door. He could feel the gust of breath through the slats. He realized how thin the door was. He cast another spell and hurried back to his own rooms. 

In the morning he let himself in. Remus was sprawled in bed, naked and bruised. He might not have become a slavering monster but he still had to transform, bones bending in all sorts of ways they shouldn’t. His eyes were open as slits and his hand curled to beckon Regulus over. He walked over and knelt by the bed. 

“You were here,” Remus said in a whisper. “You stayed.” 

“I did.”

“Why?”

“I wanted to hear what it was like.”

“I could smell you.”

He drew out the word “smell” and it sounded almost like a howl. He was hard, aching enough that he didn’t resist when Regulus wrapped a hand around his cock. It seemed the least he could do. He was getting a sense of what Remus needed. Remus resented his animalistic tendencies but knew resisting them only made them worse. He tried to stay human as much as he could. He didn’t want Regulus to fetishize them but he did want Regulus to submit to them. Regulus wanted that too. He did not want to be used. Getting fucked was fine. 

Jerking off his sick boyfriend was fine, especially when he was this responsive. His body went tense in a good way, a way that would stretch back to normal soon. His legs fell open and toes curled and Regulus thought how he had never seen him laid out like this before, their bed not exactly spacious for two grown men. The hair on Remus’ body caught the light and made him look golden where he wasn’t bruised. His voice was soft as his breath caught and when he moaned it came from a well of deep satisfaction. Regulus stroked the hair from his face and kissed him once. “Rest. I’ll teach your classes tomorrow.” 

Regulus had every class describe what they had learned so far, telling them that the only way to truly learn was to explain it themselves. Except for the first years, where he released several hinkypunks into the classroom and let them sort it out. Remus had told him about the boggart lesson so he assumed it was probably fine. He was pretty sure he heard more shrieks of laughter than terror. They didn’t know about Lockheart’s disastrous year and anyway Regulus was completely different. He could end the chaos instantly if he wanted to, he merely chose not to.

He was exhausted after a long day of teaching for two and went right to bed with no dinner. He woke in the middle of the night with Remus pressed against his back, arm tucked around his chest. 

“Feeling better?”

“What did you do to my class?”

“The usual. Hung them by their toes. Menaced them with red hot pokers.” 

“Good, wouldn’t want to deviate from my lesson plan.”

* * *

Remus woke to the sound of his own name, said softly. He opened his eyes a crack and said “hmm?”

“Remus. What do you think Sirius did?”

Remus sat up in bed. Regulus was sitting on the edge, his hands clasped between his knees. The way his back was arched made his spine prominent. Remus placed a hand against it and felt Regulus stiffen and force himself not to pull away. A moment later he relaxed, but he didn’t turn around. 

“I know what he did. We knew there was a spy, feeding information to You Know Who. The most important information was the Potters’ location. You Know Who found them, then Sirius killed Peter, who tried to confront him. Obvious.” 

“Hmm. You’re certain.”

“Why? Why do you ask?”

“You know how last year there was a… well a bit of a dust-up with a great big snake?”

“Something about that hit the papers.”

“Well, when someone starts talking about the heir of Slytherin heads begin to swivel my way. Hagrid’s got a history and a thing for beasts but after all these years he obviously wouldn’t hurt a fly. Me however… they felt it was safest to lock me up.”

Remus gasped quietly. He sat up fully, to put his arms around Regulus, his lips pressed against his shoulder. 

“Dumbledore insisted I be transported with a bag over my head. I thought it was a dick move at first but now I see he was trying to protect me. There’s a lot of people in that prison who think I’m dead and would make sure of it if they knew I’m alive. I had my own cell of course, not that that’s any comfort. I don’t know if they did it on purpose. But I wound up across from… him.” 

That time Remus went stiff. Regulus put his hands over Remus’, to stop him from pulling away.

“Could you see him?” Remus asks. 

“Yes. Remus he… he was alright.” 

“What?”

“He looks terrible, obviously, that prison is a crime itself. But he was sane. Well. He wasn’t obviously mad. Not like the others I passed on the way. He remembered me, not sure how to take that.” 

_Regulus had been huddled in a back corner of his cell, as far back as he could go which was not very far. They took the bag off his head as they shoved him inside and he clawed for it back, anything to block out the nightmare. The dementors clustered by the entrance right away and he was back in the ritual circle, back in his old robes, back in that cave screaming and screaming as his mouth filled with water and then it was empty and his throat was raw and the entrance was clear. And he understood in that moment that what had happened was only a demonstration._

_The hallway was empty of all souls but across, in the cell just across the way, was Sirius Black, draped across the bars of his cell, half-grin on his face. “Hiya Runt,” he said._

“It’s the worst place in the world,” Regulus said to Remus. “I wasn’t sure I would make it out with my mind intact and I was there a few days. He’s been there a decade.”

“Did he tell you anything?”

“No. What is there to tell?”

Remus pulled away, scrubbing his hands over his face. 

“He didn’t ask after you. I get it, he doesn’t want to know. If you’re miserable he can’t help, if you’re happy he can’t see it. I’m sorry, I know you love him.”

“Loved him.” 

“He really wouldn’t want to know that.”

“I assumed he was dead. I h-” Remus cut himself off with a huff. “Why are you bringing this up?”

“Had a nightmare. And generally can’t stop thinking about it. There’s two reasons he was so stable that I can think of. Either he was mad before he went in there. Or he’s as sane as ever which may mean- I thought maybe - was he any different, at the end?”

“I can’t tell you. Or Dumbledore. Or the Ministry. Or anyone. Everyone assumed the same thing. But we were not together.”

“But you said-”

“I loved him. And Pater, and James, and Lily, and Harry. Three of them are dead, another locked up forever. The last time I saw Harry he was an infant being shipped off to distant relatives. Everyone hoped I had the key to what had gone wrong. But it turns out I knew Sirius even less than I thought. And at the end we were all pretty distant. War will do that.”

“Why don’t you hold any of that blame for me?”

“You’re here now aren’t you?”

“You put a lot of stock in people showing up for you, don’t you?”

“I have to. I’m sorry I can’t give you any answers.”

“You were helpful all the same.”

“Come back to bed.”

Regulus slid back under the sheets, moving half on top of Remus. In the morning they had breakfast and Remus said, “Did you really think I was sleeping with your brother and now I’m sleeping with you?”

Regulus made a dismissive noise and they never talked about it again.


	2. The Body in the Lake

**Summary for the Chapter:**

> The school year hasn't officially begun until the characters confront their trauma. And I leave you with a cliffhanger.

The one bright spot in the whole Chamber Affair was that Regulus and Harry became very good friends. While other people might have been alarmed by spontaneous Parseltongue — Harry thought he was being dragged away for a telling off as Regulus maneuvered him through the corridors and away from the Dueling Club — Regulus was in fact delighted. He sent away for three pet snakes that very evening (no wonder he wound up thrown in jail, he would think later) and set up weekly meetings where the 12-year-old would translate and offer lessons. 

They figured out the noise Harry heard in the corridors must be snakes; Regulus was gearing up to go face it himself which, he admits now, did look a lot like complicity and he was dragged off to prison. So Harry went alone, reckless like his father. Luckier than his father though and Regulus was there to hear all about what happened in the Chamber. Including a name he hasn’t heard in years and a book that bleeds ink, currently sitting in Dumbledore’s office.

He would love to steal it and investigate, though it’s probably useless now. If he got the opportunity he’d take it but for now he’s not going to make a move. He doesn’t want Dumbledore to think it’s significant. He doesn’t need to know everything. Not yet. Regulus wasn’t stupid. If Harry had problems he could always come to him. He had in the past. Regulus knew this made him dangerous to Dumbledore. Regulus needed allies. People who would miss him if he were to disappear.

And then Dumbledore hired Remus Lupin. Maybe the old man was losing his touch.

* * *

Regulus has his arms braced against the headboard. He wanted to touch Remus but he needed both arms to hold himself up. He’d do anything not to change the position they were in and the angle of Remus’ hips. They were both panting, nearly there, Remus’ mouth pressed against Regulus’ shoulder. Regulus could feel his lips were bared, he could feel his teeth. He whispered “Do it, I know you want to,” and cried out when the teeth sank in. They didn’t break skin, merely holding on tight and it felt so good Regulus moaned loud enough to shock himself. He released one hand to stroke his cock and nearly collapsed under Remus. It didn’t matter because a moment later he came with another moan, louder and deeper than the one previous. Remus might have come too, he could barely tell as he sprawled on the bed under him, panting to get his breath back. 

Remus pulled out and sprawled next to him. The bed dipped as he moved and traced a circle on Regulus’ shoulder. He must have left a mark. Regulus’ face was still turned away but he smiled. Quiet behind him he heard “I’m sorry.”

“What?”

“It was impulsive. I got caught up but that’s no excuse, I’m sorry.”

“For what?”

“Biting.”

“Okay?”

“Regulus, don’t play dumb.”

He turned his head and saw Remus genuinely distressed. Regulus was bewildered. “I asked you to. Practically begged. And unless I got my date and time very confused, it doesn’t matter.”

“That’s not the point.”

“Isn’t it?”

“I don’t like being out of control. I’m normally not. All you had to do was ask once and I was… it won’t happen again.”

“Bad news for me.”

“Regulus!”

“Alright! I’m a little dismayed you’ve been holding back from me is all.”

“You’re being very calm.”

“Why shouldn’t I be? You won’t hurt me.”

“No. I won’t.”

“And since I’m so good at potions, even on a full moon night it will always be you in there. Which actually - “

“I still turn into a dog-person.”

“Okay okay fine. But I trust you and I’m stronger than I look. No holding back, promise?”

“Next time. I’m exhausted.”

“Knew you liked it.”

“That was never in question.”

“Remus.” He grunted as he moved around to fully face him. “There is no such thing as liking being in bed with me too much, I promise you that.”

He feels it the next day and has to spell his wand to do the stirring for him, which he never does in class. That day though, it wasn’t an option.

* * *

After the Halloween attack the teachers spread out to check the castle. Remus and Regulus moved the fastest. They both knew that if anyone else were to find Sirius first they would not hesitate. Remus forced himself to go to Gryffindor tower and do a thorough search, though he was almost certain that Sirius’ first stop would be the potion master’s suite in the tower across the castle. Once he was certain Gryffindor dorms were clear he went there anyway and found Regulus slumped at his workbench. 

“He’s gone.” 

“Was he here?”

“Not these rooms, no. He never came here.”

Remus sat across from him. “What would you have done if you saw him?”

“Bound him to a chair and made him answer everything. Why?”

“Why what?”

“Why did he leave?”

Remus went to him, holding him in his arms. Regulus clung to him. Remus whispered, “Yeah, me too,” into his hair.

* * *

Remus went to the Quidditch match because Regulus liked to go. They could sit in the professors box so he didn’t have to choose sides. He’s glad he went, for Harry’s sake and for Regulus’. Neither one reacts well to dementors. He could hardly blame them. 

They both made sure Harry was taken care of. His first question upon consciousness was the result of the match, a resilient and very much teenage boy. They went back to their quarters and Remus fed Regulus bites of chocolate the rest of the evening. When Regulus tired of it and complained that he did not need to be coddled Remus ate some himself and kissed him. Regulus was unable to resist and felt warmth radiate through his whole body.

* * *

Dumbledore had never looked more like an old bird than during their next one-on-one meeting. He poured the tea and waited for Regulus to speak. Regulus was good at this game and said nothing. Eventually Dumbledore sighed and decided he couldn’t waste any more time. 

“Anything new you want to tell me?”

“Nope.”

“Nothing at all.”

“Nothing that’s any of your business.”

“Everything is my business.”

“Then you should already know.”

“All I know is that since the last time we met dementors have attacked the boy who lived and your brother broke into a previously impenetrable castle.”

“Lots of things happen between our meetings.”

“Should we meet more often then?”

“Christ no.”

“How have the full moons been?”

“Is this relationship counseling now?”

“Is it a relationship?”

“Why, do I need to fill out paperwork? Because you should talk to Hooch and Sprout first.”

Dumbledore sighed heavily. 

“Look. I don’t know shit about my brother, probably less than most, and I hate dementors as much as the kid, maybe more. And you shouldn’t hire dishy kind men to be teachers if you don’t want me hitting on them. That’s all I have to report.”

“Very well.” 

Regulus went back to his lodgings, where Remus was sitting back in a chair, reading a book. It was probably for class, productive git. Regulus went to him, starting by sitting on the arm of the chair and slowly sliding down to fit in across his lap. Remus’ arm came around his waist. “How was your meeting?”

“Who cares? No, don’t,” he added when Remus started to close his book. “Don’t let me interrupt. This is fine. This is… enough.”

He had plenty to think about, wedged into the chair with his boyfriend. Not least was whether the thumb rubbing soothing circles against his hip was unconscious or deliberate.

* * *

Regulus watched Remus’ soul diminish as the year dragged on. He had gone through the same transformation though at a much slower pace. Hogwarts had saved his life, so it took him a long time to become disillusioned. 

It’s not just the dementors that drain the fun out of Remus, it was finding out what Harry had been up to while he sat there, being a perfectly capable foster father 30 days out of a month. His life under the cupboard had made Remus go numb with shock. Realizing Harry had no idea who Sirius even was had filled him with rage. Regulus was there, soothing him, knowing it made him incredibly dangerous. If Remus took his troubles to Dumbledore he could spin them with comforting half-truths. Regulus kept them soothed but stoked. Remus went back into the world pleasant and quietly nursed a grudge. Dumbledore worked by being a nexus of assurance and information. 

“I am glad though,” he said. “In a way. Because he doesn’t know about me. What I could have done if I had fought harder?”

“Oh you mean when you were twenty and had also suffered a great loss?”

“He was a baby.” 

“So were you.”

Remus grunted the way he did when he knew they were at an impasse. He was still reluctant to defy a directive from Dumbledore, implicit or not, but Regulus wasn’t. 

“Has anyone told you who Sirius is?” he asked Harry one night, while they fed his snakes. 

“I’m guessing he’s a relation,” said Harry. 

“My brother. Estranged, even before he got locked up.”

“Why?”

“He was Gryffindor.”

“Was he? I thought all the witches and wizards who went bad were from Slytherin.”

“Gryffindor propaganda. Maybe some of the worst were, but they only got away with it because lots of people from other houses turned a blind eye. But that’s the hindsight of a decade, we weren’t immune to tales told as children. My parents were awful to him and he ran away. They weren’t great to me either and I was angry at him for leaving me.”

“Is that when he went to Voldemort?”

“No. He went to your dad’s house.” 

Harry drops the box of mice. It was a good thing they were already stunned. “He what?”

“He was your godfather Harry. Sirius, James, Peter, and Remus were all friends back in school and after.”

“Peter. The one he killed. And R… Professor Lupin?”

“The very same.” He watched Harry closely for a reaction. 

“He did seem jumpy when I asked about Sirius.”

“It was hard for him. His friends either traitors or dead. He wanted to take you in, he was at Dumbledore’s office the day they took Sirius into custody.”

“Why was he told no?”

“Oh, ah. Thought it would be better you were with blood relatives,” Regulus said and then stopped. He went so quiet and so still Harry actually had to ask if he was alright. “Fine. Sorry, just had a thought. Have to catch them while I can, you know. I’m sure this is all a bit much but I thought you should know what you’re up against and you should probably hear it from someone you trust.” 

“Yeah. Yeah, thanks Professor.”

He was very glad Harry didn’t ask how he knew so much about Remus. 

“Professor?”

“Yes Harry?”

“Do you know anything about omens? Bad omens I guess.”

“The other kind are short on the ground I suppose. Why do you ask?”

“When I fell off my broom it wasn’t just the dementors. They were a big part. But they snuck up on me because I thought I saw something. A big black dog. It’s not the first time I’ve seen it. I saw in a book there’s a thing called a grimm and I thought… I can’t tell my friends, they’re already worried about me.”

“While I of course do not care one whit about your health and well being.” He did not break character and Harry smiled. “The grimm is a classic but I suspect it’s the tales of those with weak hearts who saw a large dog or wolf. To be honest with you, you have much larger and more obvious forces moving against you, I wouldn’t concern yourself seeking meaning in random sightings.” 

He hoped that worked. He suspected that since Harry had spent most of his life being lied to he might appreciate honesty for once. He did smile at least. 

“Thanks Professor.”

“I’ll keep an eye out just in case. Thank you for telling me.” 

He collapsed once he was back in his rooms. “I swear,” he said, not even looking up to see if Remus was there or not. “This job used to be easy.”

“Payback for when we were students, I expect,” he heard Remus say and that at least made him laugh.

* * *

“Remus,” he says, knowing that they were both lying awake and desperately trying not to be. “What do you know about Animagi?” He felt Remus gasp beside him. They rolled so they faced each other though they could barely see. 

“What do you know?”

“When I was in Azkaban. I saw him. He was curled up in a ball. I thought ‘who let a dog in here’ and then he looked at me.”

“Yeah, you could always tell, if you knew.” 

“How long?”

“They started the process around third year.”

“They?”

“James and Peter too. They did it to be with me on full moons.”

“Oh. No wonder.”

“What?”

“You were so distraught. Have you been alone this whole time?”

“Can’t exactly ask someone else to illegally become an Animagi can I? That’s the sort of thing teenagers think is possible.”

Regulus stroked his face. Remus placed a hand over Regulus’, holding it in place while he kissed his palm. “The potion helps. It helps me and when you develop it more it will help others.”

“Thank you. I’m still sad for you though.” 

“Thank you. But don’t be.” 

They were quiet for a long time, so lost in thought they didn’t realize they still gazed at each other, hands still clasped. 

“So were they all dogs?” Regulus asked and felt Remus’ breath as he laughed.

* * *

Regulus nonchalantly followed Harry into Remus’ classroom for his patronus lesson. He could not seem too keen, after all. He sat on the steps, eating an apple stolen from the kitchens. Hopefully, Harry didn’t think his life was so boring that he had nothing better to do than observe other teachers’ tutoring lessons. Oh God, what if his life was that boring? 

Harry massively failed the first attempt at producing a patronus. Even Regulus, who knew full well it was a bogart, felt the chill.

“What were you thinking of?” Remus asked kindly as he handed Harry more chocolate. 

“The first time I rode a broom.”

“Jesus Christ, is that the happiest memory you could think of?” said Regulus. They both glared at him. “Sorry. But. Jeez.” 

Harry’s next attempt was better, producing a light patronus-like vapor from his wand, and Remus was ready to call it a night. Harry, typically, insisted on one more try. The results were astonishing. Remus remained calm but Regulus was sat up straight, jaw open. Harry stayed conscious the whole time and when he finally lowered his wand he took one look at Regulus and grinned. “Maybe I’ll use this for the next time I need a happy memory.”

“Happy to help,” said Regulus. 

“And that’s it for the night, I insist this time,” said Remus. “Take this.” He handed Harry a full chocolate bar. “Eat the whole thing, I can’t believe I have to cajole you into eating sweets.” 

“Yeah yeah, night Professors.” Harry was already unwrapping the chocolate as he walked out the door. 

Remus sat down next to Regulus. “Sometimes I think your methods can be counter-productive.” 

“And yet.”

“I suppose you know what you’re doing. You really care don’t you?”

“Everyone thinks I don’t.”

“I think you work very hard to make it seem that way.”

“Not hard enough, obviously. Why are we talking about me? That child is a deep well of sadness where every time I think I’ve reached bottom there’s so much more. More than he’s even noticed.”

“Hmm.” Remus took out an enormous bar of chocolate and broke it in half, handing a portion to Regulus. Regulus thought he must be spending half his salary on it, he should make sure he’s sending the Honeydukes bill to the infirmary. They ate in silence for a moment, leaning against each other. “I wonder sometimes… How to put this? Not that the Muggles have everything figured out but-”

“Does knowing magic make our lives any better?”

“Yes,” Remus said, and breathed out a sigh of relief. 

“I wonder that too.” 

“Do you?” His fingers drifted along Regulus’ covered forearm. 

“Yes, quite a lot actually. You think it’s in spite of my mark but it’s because of it.”

“Would you ever leave? Snap your wand and give it all up?”

“Ah. I don’t know if I have the fortitude.”

“It’s an unfair question. I don’t even want you to. Who would make my potion?”

“Who indeed.”

Remus stroked his arm from elbow to wrist, spreading out his fingers until their hands were clasped. “I won’t have you leaving this room thinking I only like you because of the potion. Don’t you dare. The things I like about you have little to do with magic.”

Regulus was not quite sure that was true but would never be caught saying something so saccharine. He blamed the roiling emotions and copious chocolate. A kiss as an answer would suffice.

* * *

Regulus dreamed of dark waters closing in over his head, a thousand bodies swarming around him and one brighter than all the others stands out among them, lying poisoned and prone on a jagged slab of rock.

It wasn’t the first time he’d had the nightmare. It was the first time he’s had it in class though. The sixth year students were making sleeping potions. That class was made up of Ravenclaws and Hufflepuffs who excelled at classwork in general and sleepytime tea in particular so it was not his fault. He gave them points for a job well done and extra points if they kept it to themselves that he fell asleep. He knew it was only partially the fumes as he and Remus both hadn’t been getting much sleep. Not due to some sex marathon or unhappy tossing and turning, they merely lay there in each others’ company. Regulus knew his own heart was thudding so fast he would never sleep and stopped trying; he suspected Remus felt the same. He blamed all the reminiscing, it had them acting like teenagers again. 

They’d been child soldiers when they were actual teenagers, it was only fair they got to be silly as adults. 

The dreams during the day disturbed him though. He’d been having that dream a lot lately but it did not make it any easier. One, because he suspected his unconscious felt guilty and wanted him to do something about it. Two, because he was quite sure that if he had the dream enough times he would do something about it. Three, because it wasn’t a dream. It was a memory.

When Voldemort told him about the magic of horcruxes he had seen the light of ambition in Regulus’ eyes. That was how Regulus survived that encounter. When Regulus heard that news he’d known exactly what to do. He found the only potion master who rivaled his skill and outclassed him in desire for knowledge. He told Severus everything. 

What Regulus told himself every year after was that he never once lied to Snape. When he had him drink the burning poison in the cave he only said “every great transformation will be painful.” He never looked away while Severus writhed in pain until he went still. He never saw recrimination in his eyes. 

But he still did it. He knew what he was doing. Killing two birds with the same stone that would save his house elf’s life. He killed the worst spy for the death eaters and set a ticking time bomb for their leader. 

He’d had a hard time getting out of that cave and for a while he thought that was enough penance. His subconscious seemed to disagree. Perhaps he could be forgiven murder but he wasn’t allowed to be happy. That must be why the dreams returned in force when Remus came into his life. Survival was permitted but joy was more than a murderer deserved. 

He would tell Remus at the end of term. He’d be leaving school anyway, the curse still alive and well after all. And he didn’t want to disrupt the classes any more than necessary. He could not envision a future where Remus forgave him.

* * *

“Hermione and Ron, you can work together over that cauldron. Whatever you are fighting about now I don’t care, get to work.” 

Ron muttered something and Regulus didn’t care except he caught “cold blooded murder” and he stopped in his tracks and wheeled on them both. 

“Excuse me?” he said, his voice so icy every student who heard looked up immediately. Ron went even paler than usual and shrank in his robes. 

“Nothing, Professor.”

“He thinks my cat ate Scabbers,” Hermione said, voice shaking only a little. When Regulus’ face became only more bewildered she added meekly, “his rat.”

Regulus stared at them both while he mastered his emotions. He refused to even glance at Harry, unwilling to get any idea of what he must be thinking. 

“I see. Hardly unusual behavior for a cat, is it? I hope my condolences will be enough to stop this from disrupting class any further.”

* * *

“Harry asked me about the night his parents died,” Remus said. “He opened by saying he wasn’t mad I wasn’t able to adopt him. Remarkable boy.” 

“He’s something isn’t he? Incredibly naive and also wise beyond his years. Truly something. He came to me today to apologize for his friends even though I was the one out of line.”

“Oh were Hermione and Ron squabbling again?” 

“Yes!”

“I’ve been tempted to tell them off myself once or twice. What was it this time?”

“Her cat ate his rat.”

“That is rather gruesome.” 

“Harry explained the rat has been in the family for years, given to him by his brother, so it was a long-standing relationship I suppose.” 

“Huh. Old rat.”

“Indeed. It was going to shuffle off this mortal coil soon enough anyway. At least it offered a cat some nourishment as it went.”

* * *

Regulus was nearly done with his scheduled security sweep of the school. Remus had offered to help so they could split the difference and be done sooner. There was a twinkle in his eye when he said it. Regulus had to force himself to be thorough and not hurry along his search too much. He was about to head back to his rooms when he noticed a small point of light disappear around a corner. He hurried after it, his own wand drawn, keeping his footfall light as he could. He turned the corner himself and saw the light go out. 

“Stop! Who goes there?” 

He heard a weary sigh. Then Harry said, “Sorry, Professor. I thought I saw something.” He reignited his wand and Regulus saw he was carrying a complicated bit of parchment. 

“What is that?” 

What Harry showed him took his breath away. It was some of the most remarkable magic he’d ever seen. A lot of mysteries around many of the students suddenly became very clear. They were still poring over the map when Remus appeared at the other end of the hall. He smiled when he saw them and looked so handsome standing there, genuinely happy, Regulus smiled back. 

It all faded as Remus got closer. All the color drained out of his face, the mirth from his eyes. 

“How-” He snatched the paper from Harry’s hands. His eyes were huge as he looked it over. “Where did you find this?”

“I uh- Filch’s office,” he said. Regulus thought it was obvious he was lying but he was paying more attention to Remus, who was fully absorbed by the map. 

“And did you not think this might be a security risk?”

“Er, what?”

“That this map, in the wrong hands, is a map directly to you?”

He clearly hadn’t. He looked down, ashamed. Regulus’ instinct was to comfort him but held back, knowing Remus had a point. For all they wished to believe Sirius had misunderstood extenuating circumstances, the evidence was very much in favor of Harry being in great danger. Indisputable when it came to people besides Sirius anyway.

“What were you even looking for?” Regulus said. 

“Nothing.” Harry clearly hoped to leave it at that but Regulus stared at him until he mumbled the real answer. “I thought I saw Peter Petigrew on that map.”

Both Remus and Regulus went very still. 

“That’s not possible,” Remus said. 

“Perhaps the map made an error,” said Regulus. 

“The map never lies.”

Both Regulus and Harry stared at Remus. He ignored them. 

“I’ll be keeping this from now on. Go to bed Harry. If you don’t go straight to your dorms we will know.” 

He nodded. “Good night, Professors.” 

Back in their rooms, they spread the Marauder’s Map out across their table. There they were, their names printed in floating scroll work, hovering gently next to each other. Well, that might explain why Harry hadn’t felt the need to ask why they shared so much information. 

Regulus glanced at Remus, who stared at the paper but wasn’t really looking. “So. You’re Padfoot I take it.” 

He shook his head. Regulus thought maybe he’d gotten everything wrong when Remus said in a hoarse voice “Moony.” 

“Oh of course. It’s a really incredible piece of work.” Remus nodded. “What he saw--”

“It’s late. He must have gotten confused.” 

“Probably. Are you going to come to bed tonight?”

Remus still stared down at the map, which Regulus supposed was an answer. 

“Alright then. Goodnight Remus.” He started to go to bed himself. “Oh! Wormtail and Prongs, I get it!” He laughed softly as an idea gently floated into his mind, fully formed. It slotted into his narrative with a cheerful thump, the way a book slides into a perfectly full bookshelf. He grabbed Remus by the arm. It was violent enough to shake Remus out of his stupor and they looked at each other, eyes wide. “Wormtail.”

“What about him?”

Regulus turned the idea over and over in his head and could find no fault in it. Especially because of one thing: he had heard that nickname before. 

“I’m going to feed that man to my snakes.”


	3. Rat, Snake, House Elf

**Summary for the Chapter:**

> The thrilling conclusion of The Prisoner of Azkaban if Regulus Black was in control of everything.

Regulus didn’t look away from the cage they kept suspended in the air. He said “Remus. Do not move. I’m getting Dumbledore.” He ran as fast as he could, not even slowing down to say the password. He burst into the room to find Dumbledore having tea with Cornelius Fudge. 

“I say!” said the Minister of Magic.

“Perfect. Can you both come to my office?”

“I beg your pardon?”

“Right now? Please?”

Dumbledore looked tired and about to protest as well, but he saw the look on Regulus’ face. A look he’d never seen before. When he’d come unbidden to this office before, just the one time, he’d been calm. Calculating. He had never been this out of sorts ever, in his life, even when drenched and covered in muck. Dumbledore stood.

“I think perhaps this is as urgent as he says.” 

As they walked down the hall Regulus saw the little blond second-year who was clearly in love with Harry. He tried to be as un-scary as possible when he crouched down and told him, Creevy was it, to tell Harry to report to the potions room as quickly as possible, it was to do with their snakes. The boy nearly tripped over himself as he ran off. 

“What is this all about?” said Fudge. 

“All will become clear in time. I’m here to make your job a whole lot easier though, I promise you that.” He could hear how his voice had gone slightly hysterical. 

“I’m not sure how that’s possible but we shall see,” Fudge said with some asperity. 

They entered his office to find Remus rooted to the spot, eyes not leaving the terrarium or the three snakes who hadn’t had feeding time in two weeks and the box hovering over it, where a large garden rat scrambled frantically. 

“What on earth is this?” Fudge demanded. 

“We’d like to report an unregistered Animagus,” said Regulus. He went to the terrarium and tapped the lid, which vanished. The rat in the cage squeaked in alarm. 

“There are departments for that! You brought me all this way just for-”

“When Peter Pettigrew was killed all they could find was his finger, isn’t that correct?” Remus spoke in a flat voice, eyes only on the rat in the cage. 

“Yes but what does that have to do with-”

“Peter Pettigrew was an Animagus. He took the form of a rat.”

“So if you wouldn’t mind inspecting this rat here?” said Regulus. 

“I’ll do no such thing!” 

“Very well,” said Regulus. “Sorry, my dears,” he said to the snakes and then vanished the bottom of the rat cage. 

That was the moment Harry arrived in the office. He walked in on the Prime Minister shouting, three wizards leveling their wands at a fourth, and three very upset snakes escaping across the floor. 

“That’s Peter Pettigrew,” Harry said. “He’s! He’s here!” 

“So it is,” said Dumbledore. “Fascinating.” 

Regulus couldn’t stop smiling. He had still had his doubts, right until the end. “Harry, do you mind seeing to the snakes for a while? They’re upset and deserve a treat. I think Remus and I have a lot of explaining to do.”

* * *

They told Harry of course, their own version. And staged a reunion, though after their own. 

There had been a sobering moment, after Peter was led away in chains, when they realized they might still be too late. Sirius was presumably innocent yet he’d been in Azkaban for twelve years. He hadn’t been completely gone when Regulus had seen him but that was a long way from sane. They would intervene before introducing him to a thirteen-year-old. First they needed to find him. 

“I have an idea,” said Remus. “Will you come to Hogsmeade with me?”

“A date? Now?”

“No, you git.” 

They walked into the Shrieking Shack with wands away but at the ready.

“Sirius? Padfoot?” Regulus called. “We found Peter. And the dementors are gone. You can come out now.”

The dog that walked out was enormous, nearly a bear in size. Regulus watched closely as it shifted but his eyes could not comprehend the moment the dog became his brother. He looked the same as he did in prison: gaunt, dark circles around his eyes, hair hanging down around his head. “Regulus? You’re here?” He looked up. “Remus?”

“We know what happened. And the Minister knows too. Sirius. It’s over.” 

Sirius sat down with a thud, his head in his hands. It felt odd to let him sit there, obviously weeping, yet too soon to go to him. Both Remus and Regulus stood over him, watching it happen. After a while he said “I wanted to be the one to kill him.”

“Ok well don’t say that to anyone else, we’re trying to get you a pardon for that murder,” said Regulus. Remus shot Regulus a dirty look. “What? Anyway, he’s not dead. We need him around to exonerate you. I did scare him half to death though, if that makes you feel better. I’ll show you in a Pensieve sometime. It was worth giving the snakes a bit of a jolt. Harry told me later they didn’t even mind, once he explained it all.” 

Sirius stared at him with an expression that made it clear he was wondering if he truly had gone mad. That was how Regulus knew he was going to be fine. “C’mon,” he said, punching his arm. “Let’s get you cleaned up so you can meet your godson.”

* * *

Regulus thought nothing about taking his brother back to their rooms until Padfoot changed back into Sirius and looked around. Then it became immediately apparent that Remus and Regulus lived together. He saw Remus turn bright red. 

“Go down to the kitchens and get us some food would you?” Regulus said. “I assume you know the way.” 

Remus nodded and escaped quickly. 

“Well,” said Sirius. 

“So dies the most noble and ancient house of Black.” 

Sirius’ sputter of laughter turned into a guffaw. It was scratchy, out of practice, but genuine and lovely to hear. Regulus heated water for the tub and looked away as Sirius got in. 

Regulus wasn’t sure about what to do about sleeping arrangements until after their dinner when Sirius sighed deeply, pushed his chair back from the table, and shifted into Padfoot. He turned in a circle three times and curled up in a corner where he closed his eyes and was snoring within minutes. Regulus looked to Remus, who was staring, mouth ajar. 

“Old habits?” Regulus said. 

“Guess so.”

Regulus vanished the remains of dinner with a wave of his hand. Remus gestured toward the tea set to summon it to them. Regulus was about to comment when Remus also picked up the whiskey. 

“We’ve got to talk,” Regulus said, voice soft so Padfoot could get his sleep. “About our shared bad habit of falling in with whoever is nearest.”

Remus passed him a teacup and the whiskey, allowing Regulus to spike it however generously he wished. Very, was what he wished. “I don’t think that’s it,” said Remus, whose voice was always soft. “It’s whoever stuck around. And can you blame me for that?” 

“Hmm.”

“Peter was our friend, at first. For a while. I believe that. I’ve been thinking about which is worse, if our entire friendship was a lie or if he chose to betray us. I’d prefer to think we were happy once. There were good times. And yeah, what is life but making the best of what’s available to you?”

Regulus couldn’t even muster a grunt that time.

“Reg.” He looked up. Remus was looking right at him, a searing amount of eye contact. “I didn’t come to Hogwarts looking for a boyfriend.”

“Surprise!” said Regulus. It was louder than he intended and one of Padfoot’s ears twitched. But he did feel better. Casually, he let his hand rest on the table. Remus took it immediately. He brought it to his mouth and kissed his knuckles and kept holding it when he placed it back on the table and drank more of his tea. 

Regulus tried to wake up early but Sirius was already up, sitting at the table with a copy of the Daily Prophet and a laughably small owl eating crackers off of a plate. Sirius was assiduously not looking at the bed. 

Regulus sat up as smoothly as possible, hoping not to disrupt Remus behind him. He got dressed and put on his walking shoes. 

“Where are you going?” said Remus sleepily, lifting his head from the pillow. 

“Hogsmeade.”

“What for?”

“To pick up a present for Kreacher.”

Sirius spit out his breakfast tea. “What for?!”

“Who do you think caught Wormtail sneaking around the kitchens?”

He smiled at both of their astonished faces and slipped out of the room before they could comment further. They needed their time to talk.

* * *

After all that Remus and Regulus still had to proctor exams. Both of their disciplines were mostly practical and they finished grading in an evening, at nearly the same time. They looked up at each other after the first normal evening they’d had in weeks. No research, traps, spying, or interrogation. 

“I used to think,” said Remus “How could we have been recruited as soldiers and spies? We were so young, how could that be expected of us. Now I think, how could it not? I’m exhausted.” 

“Yes I suppose you’re right. It’s too bad is all.”

“Oh. Well.” A sly smile spread across his face. Regulus grinned eagerly and bumped the table when he got up. Remus slumped in his seat, making his lap a very inviting place to sit. Regulus maneuvered himself into Remus’ chair. It’s Hogwarts issue so they’ll have to move soon. He felt not so old anymore as Remus’ hands slid up his sides and down his hips, squeezing his ass. Regulus leaned in, brushing noses and lips. It felt like ages before they actually kissed but even though they felt down to their bones how long it’s been since they’ve had time for this they weren’t in any rush. Hardly everything was right in the world but when they were like this it felt like maybe it could be. When they finished there will be more work to do, both determined to not push any more responsibility on students who are still children, so for the moments they had they were determined to take their time. 

The chair started to make an alarming creaking noise so they moved to the bed. “I hope the bed in your cottage is roomier,” Regulus said, pulling his shirt over his head. Remus smoothed the hair around his face. 

“It is. You can lie across it diagonally and not fall off.”

“Mmm. Lots of room to maneuver. And hefty silencing charms I’m sure.” 

He would not have presumed to be spending the summer with Remus, except Sirius was told to be there so obviously Harry will be joining them and by that point it was assumed Regulus was also invited. One more reason Sirius had, late in life, started to make Regulus’ life easier for once. The first time Regulus spoke about staying there with them like it was a forgone conclusion the look on Remus’ face told him everything he needed to know and he got a book on home protection spells from the library. It was in the restricted section, not because the spells were especially dangerous or complicated, but too many students had put up wards around their beds and trunks and created minefields of magic within the castle so the book had to be locked away.

In the back of his mind, Regulus wondered if his role would be less assisted child-care and more brotherly anger-management but he does not bring up his concerns yet. He won’t upset them too early, not until he’s certain.

“I’ll transform in the field outside,” Remus said, pulling his own clothes off and casting them aside. 

“Idiot. That’s not what needs to be silenced.” Regulus grabbed for him, making room for Remus on top of him. “I don’t plan on being celibate around you, just because my brother and godnephew are underfoot.” 

“I see.” 

“You blush a lot for someone who is about to be inside me.” 

“Oh shut up.” 

Regulus laughed until Remus’ kisses forced him to stop.

* * *

“Tell me about him,” Sirius said. 

“He’s still in love with you,” Regulus blurted out. Sirius looked up, shocked. Not shocked by love but still, surprised. “He never wanted to believe it of you. He wasn’t heartbroken by what you’d done, he was heartbroken it was you who’d done it.” 

“That’s unfair, he loved James too. And Lily and Harry. And Peter, in his own way. You never saw him?”

Regulus shook his head. “Only heard his code name. I got out right before he got in. My timing sucks.” 

“What I don’t understand is how they knew what to ask. How did they even know there was a secret-keeper?”

“Snape.”

“What?”

“Severus Snape. I did know him.”

“What happened to him?”

“I killed him.”

Sirius’ eyes widened. “So, of the two of us.”

“I’m the murderer, yes, I get it. I’ve had my own way of dealing with it.” 

“I’m going to guess Dumbledore knows and Remus doesn’t.” 

“I’ll break it to him eventually.”

“I don’t think there’s any love lost there. If he never stopped loving me all might not be lost for you.”

“I’ll tell him during the summer, just in case. Wouldn’t want him to have to move twice so quickly. He can kick me out while my things are mostly packed up. I hope he does. Or decides he loves me anyway. He’s kind enough to stay out of obligation, and I don’t want that. And he’s funny. And a surprisingly dark sense of humor. And, well. Other things.” 

“I see.”

“Are you mad at me? Were you in love with him?”

“No. Yes. I loved him. Everyone loved him. Despite what he says he’s very easy to love. But I’m not mad. It was never right. We failed each other too many ways for anything to be possible. That we can ever be friends is miraculous. I’m happy with that.”

“You’ll be sick to death of all of us by summer’s end.”

“Probably.”

Regulus smiled. He’d never actually seen where Remus lived. Perhaps it was less the idyllic country cottage he imagined and more of a crumbling hell hole. He thought about the other places where he’d lived and decided he would be able to make do, at least for one summer.

* * *

Dumbledore appeared in Regulus’ rooms on the last day of term. He’s never been there before, their meetings previously always confined to Dumbledore’s office. Regulus was going through his potions ingredients, checking which ones needed to be used up so they didn’t explode while he was away. He looked up to find the headmaster standing in the doorway.

“You missed our appointment.”

“Are we still doing that?”

“The circumstances surrounding our arrangement have not changed.”

“I caught another Death Eater spy for you, I thought I might be entitled to a month off.” 

“Incorrect.”

“I told you everything I know.” 

“Nothing new has occurred?”

“Nope, but I’ll send an owl in case anything pops to mind.”

“An owl? Could you not simply walk to my office?”

“Quite a long walk, from Remus’ cabin.”

“I see. You know I can’t extend my guarantee of protection that far.”

“Yeah. But they’ll need help looking after Harry.”

He said it as casually as he could. When he turned to look at Dumbledore he saw a pitying expression on his face. An expression that turned sour, once he realized Regulus was only playing at being that naive. Everyone always underestimated what Regulus noticed. Even though he was the one who discovered Pettigrew, they still underestimated him. 

“So he has to go back to those Muggles?” he said. 

“He’s safer with blood relatives.”

“Who hate him. But his appointed guardian, who adores him, is not good enough?”

“That’s correct.”

“Good. I wanted to hear you say it.”

“Am I to consider this your resignation?”

“You wish,” said Regulus. He’d lost his cool once this year, that was plenty. 

Dumbledore left and Remus returned and they finished packing up their things to be ready to leave right after the closing feast. It didn’t take long, they only needed the bare essentials for the summer. They meant to spend it relaxing, some of it in bed if they got any privacy. They’d both be back in the fall and Regulus would be on his best behavior. If his suspicions were correct at least two more horcruxes were Dumbledore’s very office, with more likely elsewhere in the castle. He would need to stay nearby to get his work done. If he stayed in Dumbledore’s good graces he could have Voldemort destroyed by Halloween with no one the wiser.

**Notes for the Chapter:**

> That's all folks. Hope you enjoyed it!


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